Runs discount supermarket group Aldi Nord; firm holding up amid economic downturn. Sales expected to hit $31 billion in 2008. After World War II he and older brother Karl transformed their mother's corner grocery into Aldi. Brothers split ownership in 1961; Karl took the stores in southern Germany, plus the rights to the brand in the U.K., Australia and the U.S. Theo got the northern Germany stores and the rest of Europe. Unable to operate Aldi stores in U.S., Theo developed discount food store Trader Joe's; now has more than 320 U.S. stores. Also owns stake in Supervalu. Became a recluse after being kidnapped for 17 days in 1971; said to collect old typewriters; loves golf.